Crohn's disease

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Inflammatory bowel diseases are chronic inflammatory diseases of the bowel that are of unknown etiology. These diseases either progress with intermittent flare-ups interrupted by periods of remission or on a chronic active progressive mode. Inflammatory bowel diseases include Crohn disease and ulcerative colitis. Clinical and imaging diagnosis often is challenging, hence explaining the frequent time delay between onset of disease and initiation of therapy.
Crohn disease usually presents with pain, diarrhea and weight loss. 

 Sonography
 The terminal ileum/ileo caecal junction is involved in the majority of cases, and thickened; hypoechoic bowel wall can often be demonstrated in this area. Inflammatory thickening of the intestines is generally diffuse and concentric
 In Crohn's lesions there is a well-defined echopoor outer rim and a bright inner region; transverse scans may demonstrate a target lesion.  The bowel thickening may be focal or found over long segments, characteristic skip lesions may be observed.  A wall thickness greater than 3 mm is considered abnormal. Ultrasound may be used to identify complications of Crohn's disease, screen patients at risk, and monitor patients for recurrence of disease following surgery.
 Crohn's disease affects the entire thickness of the bowel wall, and one of the common complications is that of intramural abscesses. These can sometimes be seen within the thickened wall as gas-containing, highly echogenic areas. When large, they may perforate, resulting in an ill-defined collection of pus, which may be drained percutaneously.
Fistulae are another complication of Crohn's, and are easier to demonstrate with contrast radiography.
 Inflammatory bowel diseases increase the perfusion of the intestine, decreasing vascular resistance.
In both Crohn's and ulcerative colitis compared with normal subjects. Doppler of the SMA reveals an increase in flow velocities : both peak systolic and end diastolic, and a decrease in resistance index in numerous types of pathological bowel, including Crohn's.
 In patients with active Crohn's disease the flow is 826 ± 407ml/min (range 242-1455ml/min).  A certain overlap is present.  If the threshold value of less than 5OOmL/min is used, a sensitivity of 83 pet cent and specificity of 87 pet cent can be achieved for active Crohn's disease. 
 Changes in resistance index have been found to be related to the activity of Crohn's disease, which could prove valuable in monitoring patients with known disease.
Intravenous contrast agents may help to differentiate fibrotic and inflammatory strictures, and to discriminate inflammatory masses from intra-abdominal abscesses.
 The sonographic detection of enlarged regional lymph nodes is more frequent in young patients, which suggests an earlier phase of Crohn's disease and the presence of septic complications such as fistulas and abscesses.
 Crohn's disease is associated with fatty liver, hepatic abscesses, gallstones, cholecystitis, sclerosing cholangitis, hepatocellular carcinoma, bile duct carcinoma, renal calculi and renal amyloid. 

Differential :
Another condition that can produce bowel thickening is :
* Colitis (Ameobiasis. Pseudomembranous colitis. Necrotising enterocolitis).
*Appendix .
* diverticulitis
* intussusception
* Ileocecal tuberculosis
*Abscess.
*Oedema - hypoalbuminaemia, portal hypertension, constrictive pericarditis.
*Zollinger-Ellison syndrome.
*Cystic fibrosis.
*Sprue.
*Protein-losing enteropathy.
*Cancer chemotherapy.
*Ischaemia and intramural haemorrhage.
*Venous congestion including malrotation and chronic volvulus.
*Intestinal lymphangiectasia.
*Henoch-Schônlein purpura (this may accentuate the mucosal pattern).
*Pelvic inflammatory disease.
*Trauma.
*Gastroenteritis (including eosinophilic enteritis).
*Giardiasis.
*Yersinia ileitis.
*Campylobacter ileocolitis.
*Salmonella ileitis.
*Anisakiasis.
*Amyloidosis.
*Whipple's disease.
*Giardiasis or strongyloidiasis.
*Behçet's syndrome, the appearance is similar to Crohns disease.
*Radiation.
*Lymphoma.
*Coeliac disease.
*Dermatomyositis.
*Adenocarcinoma.
*Tumeurs including métastases*.
*Pneumatosis intestinales.
*Peritonitis.
*Kaposi's sarcoma.

Ultrasound is helpful in differentiating tubo-ovarian pathology.

References :
* 1 De Pascale A, Garofalo G, Perna M, Priola S, Fava C. Contrast-enhanced ultrasonography in Crohn's disease. Radiol Med (Torino). 2006 Jun;111(4):539-50. Epub 2006 May 25.
* 2 Maconi G, Radice E, Greco S, Bianchi Porro G. Bowel ultrasound in Crohn's disease. Best Pract Res Clin Gastroenterol. 2006 Feb;20(1):93-112.
* 3 Maconi G, Di Sabatino A, Ardizzone S, Greco S, Colombo E, Russo A, Cassinotti A, Casini V, Corazza GR, Bianchi Porro G. Prevalence and clinical significance of sonographic detection of enlarged regional lymph nodes in Crohn's disease. Scand J Gastroenterol. 2005 Nov;40(11):1328-33.
* 4 Fraquelli M, Colli A, Casazza G, Paggi S, Colucci A, Massironi S, Duca P, Conte D. Role of US in detection of Crohn disease: meta-analysis. Radiology. 2005 Jul;236(1):95-101.
* 5 Parente F, Greco S, Molteni M, Anderloni A, Maconi G, Bianchi Porro G. Modern imaging of Crohn's disease using bowel ultrasound. Inflamm Bowel Dis. 2004 Jul;10(4):452-61.
* 6 Ludwig D. Doppler sonography in inflammatory bowel disease. Z Gastroenterol. 2004 Sep;42(9):1059-65.
* 7 Neye H, Voderholzer W, Rickes S, Weber J, Wermke W, Lochs H. Evaluation of criteria for the activity of Crohn's disease by power Doppler sonography. Dig Dis. 2004;22(1):67-72.
* 8 Di Sabatino A, Armellini E, Corazza GR. Doppler sonography in the diagnosis of inflammatory bowel disease. Dig Dis. 2004;22(1):63-6. 9 Sturm EJ, Cobben LP, Meijssen MA, van der Werf SD, Puylaert JB. Detection of ileocecal Crohn's disease using ultrasound as the primary imaging modality. Eur Radiol. 2004 May;14(5):778-82. Epub 2004 Feb 4.
* 9 Hirche TO, Russler J, Schroder O, Schuessler G, Kappeser P, Caspary WF, Dietrich CF. The value of routinely performed ultrasonography in patients with Crohn disease. Scand J Gastroenterol. 2002 Oct;37(10):1178-83.
* 10 Meckler U. [Ultrasound diagnosis of Crohn disease] Schweiz Rundsch Med Prax. 2002 Apr 3;91(14):591-6.
* 11 Rubini B, Jaafar S, Gaucher H, Kissel A, Gobertier-Gasparini G, Fromaget JM, Tabary D, Muller M, Etzel JC. [Value of sonography in the diagnosis and follow-up of patients with cryptogenic inflammatory bowel diseases in current practice: review of a 10-year experience in a community hospital] J Radiol. 2001 Nov;82(11):1601-11.
* 12 Valette PJ, Rioux M, Pilleul F, Saurin JC, Fouque P, Henry L. Ultrasonography of chronic inflammatory bowel diseases. Eur Radiol. 2001;11(10):1859-66.
* 13 Esteban JM, Maldonado L, Sanchiz V, Minguez M, Benages A. Activity of Crohn's disease assessed by colour Doppler ultrasound analysis of the affected loops. Eur Radiol. 2001;11(8):1423-8.
* 14 Spalinger J, Patriquin H, Miron MC, Marx G, Herzog D, Dubois J, Dubinsky M, Seidman EG. Doppler US in patients with crohn disease: vessel density in the diseased bowel reflects disease activity. Radiology. 2000 Dec;217(3):787-91.
* 15 Limberg B. [Diagnosis of chronic inflammatory bowel disease by ultrasonography] Z Gastroenterol. 1999 Jun;37(6):495-508.
* 16 van Oostayen JA, Wasser MN, Griffioen G, van Hogezand RA, Lamers CB, de Roos A. Activity of Crohn's disease assessed by measurement of superior mesenteric artery flow with Doppler ultrasound. Neth J Med. 1998 Dec;53(6):S3-8.
* 17 Giovagnorio F, Diacinti D, Vernia P. Doppler sonography of the superior mesenteric artery in Crohn's disease. AJR Am J Roentgenol. 1998 Jan;170(1):123-6.
* 18 Maconi G, Bollani S, Bianchi Porro G. Ultrasonographic detection of intestinal complications in Crohn's disease. Dig Dis Sci. 1996 Aug;41(8):1643-8.